Multiple myeloma, which is a typical example of a disease causing neoplastic growth of plasma cells, accounts for about 1% of all cancers, and accounts for a little more than 10% of all hematological malignant tumors. Multiple myeloma is a disease in which a plasma cell present in bone marrow becomes cancerous (becomes an abnormal plasma cell as a result) and undergoes monoclonal growth.
In multiple myeloma, abnormal plasma cells (myeloma cells) spread to the bone marrow throughout the body and grow in every part of the bone marrow throughout the entire body. When the abnormal plasma cells grow, various symptoms including bone breakage appear. The myeloma cells produce M protein, which is an abnormal immunoglobulin, to increase an M protein concentration in blood, and hence the blood becomes viscous.
The M protein does not function as an original antibody, which recognizes a foreign substance, such as a pathogen, which has entered the body. Accordingly, immunocompetence is reduced. Those phenomena affect many organs, and thus various symptoms occur. Typical symptoms are bone pain and damage, hypercalcaemia, nephropathy and renal failure, anemia, and the like.
At present, as treatment of multiple myeloma, proteasome inhibitors, iMIDs, such as thalidomide and a derivative thereof, specifically lenalidomide, and chemotherapy using, for example, melphalan in combination with prednisone, and hematopoietic stem cell transplantation are mainly employed.
However, the myeloma cells eventually acquire resistance to those therapeutic agents in most cases. Accordingly, the reality of the current treatment means is that a myeloma patient has an unpromising prognosis with a mean survival period after onset of from about 3 years to about 5 years. In addition, those therapeutic agents do not specifically act on only tumor cells serving as targets, and hence have a problem of showing toxicity also to normal cells, consequently causing serious side effects.
There have been attempts to develop a treatment method for multiple myeloma utilizing a monoclonal antibody. For example, an anti-CS1 antibody, and an anti-CD38 antibody, and the like are considered promising (Non Patent Literatures 1 and 2). In addition, in Patent Literature 1, there is disclosed a therapeutic agent for multiple myeloma or the like, which uses an anti-human CD48 monoclonal antibody as an active ingredient.
Integrins mainly form a heterodimer of an α-chain and a β-chain to serve a function as a receptor on a cell surface in a living body. There are many combinations of α-chains and β-chains of such integrins.
In addition, in Non Patent Literatures 4 to 6, there are disclosed chimeric antigen receptor T-cells (CAR-T cells) including an antigen recognition site having an affinity for a certain antigen.